Facile Synthesis of Azaspirocycles via Iron Trichloride-Promoted Cyclization/Chlorination of Cyclic 8-Aryl-5-aza-5-tosyl-2-en-7-yn-1-ols

A simple and efficient FeCl3-promoted cyclization/chlorination of cyclic tosylamine-tethered 8-aryl-2-en-7-yn-1-ols was observed. The reaction proceeded instantaneously at 23 °C in air to afford (Z)-4-(arylchloromethylene)-substituted azaspirocycles in good to excellent yields. This transformation can also be applied to the synthesis of spirocarbocyclic analogues from cyclic 8-aryl-2-en-7-yn-1-ols and FeCl3.

本研究发现，三氯化铁（FeCl₃）可促进连有环型对甲苯磺酰胺基团的8-芳基-2-烯-7-炔-1-醇发生简便高效的环化/氯化反应。该反应在23℃、空气氛围下瞬时进行，能够以良好至优异的产率得到(Z)-4-(芳基氯亚甲基)取代的氮杂螺环化合物。该转化策略同样可应用于以环型8-芳基-2-烯-7-炔-1-醇与三氯化铁为原料合成螺碳环类似物。